Infinitely variable belt or chain drives for automotive vehicles usually include adjustable sheaves that are connected by a belt or chain. The ratio of the drive is changed by appropriately adjusting the effective pitch diameter of the sheaves. This is taught, for example, by Moan U.S. Pat. No. 3,315,049, assigned to the assignee of this invention, and by Smirl U.S. Pat. No. 4,433,594. The ratio range can be extended by incorporating torque transmitting gearing in the torque flow path defined by the sheave assembly. Examples of infinitely variable drives with extended ratio ranges can be seen in Omitsu U.S. Pat. No. 4,354,401; Stockton U.S. Pat. No. 3,304,803 and General U.S. Pat. No. 3,203,278. The General and Stockton patents are assigned to the assignee of this invention.
It is common practice, furthermore, to use in combination with the gearing and the infinitely variable portions of the driveline a fluid coupling or torque converter either to extend the ratio range or to provide smoothness in the torque delivery. This is shown in the Stockton and General patents as well as Moore U.S. Pat. No. 3,125,900. Unlike the present invention the Stockton and General patents show an infinitely variable friction drive rather than a belt and sheave assembly, but those references do show the concept of combining a gear system with an infinitely variable unit. The Moore patent, which also is assigned to the assignee of this invention, does not show an infinitely variable drive but rather a positive chain drive in combination with a torque converter and a gear system.